Interaction between delta-9-tetrahydrocannabinol and indomethacin.

The effect of indomethacin on the Delta9-tetrahydrocannabinol (Delta9-THC)-induced fall in rabbit intraocular pressure (IOP) was determined. A 2% suspension of indomethacin was given topically 1 h before intravenous injection of Delta9-THC. IOP was measured hourly and was compared between groups receiving either Delta9-THC alone or Delta9-THC plus indomethacin. A substantial attenuation of the IOP response to Delta9-THC was caused by indomethacin. Delta9-THC may influence IOP at least in part by a prostaglandin-mediated process. Involvement of the cyclooxygenase pathway offers a common explanation for linking several ocular cannabinoid effects. The latter include a fall in IOP, conjunctival hyperemia and minor inflammation.

Influence of dehydroepiandrosterone on rabbit intraocular pressure.

PURPOSE: The systemic concentration of dehydroepiandrosterone decreases with age in primates while in humans intraocular pressure (IOP) increases with aging. This study was designed to investigate if a relationship existed between dehydroepiandrosterone and IOP in pigmented rabbits. METHODS: Animals were treated unilaterally for 6 weeks with topical 3% dehydroepiandrosterone in 30% 2-hydroxypropyl-beta-cyclodextrin; the contralateral eye received vehicle alone. Drops were applied, and IOP measured, twice daily. RESULTS: Small, but statistically significant, drug-related effects were found. IOP was consistently higher in the afternoon; the afternoon minus morning difference in IOP, however, decreased with time. Topical, radioactive drug application indicated very low level penetration into aqueous humor, iris, corneal epithelium, the rest of the cornea, or bulbar conjunctiva. CONCLUSION: The small drug-related effects may be due, in large part, to poor intraocular drug penetration. The circadian rhythm of IOP appears to be time-dependent in chronic studies with a gradual loss of IOP difference between a.m. and p.m. readings.